Following example demonstrates how IO::readln and IO::println are mutually blocking and how IO.println behaved differently than System.out.println in multithreaded code.


```
static void doSomething() {
    try {
       Thread.sleep(1000);
   } catch (InterruptedException ignore) {}
}
 
void main() {
   Thread.ofVirtual().start(() -> {
        while (true) {
            doSomething();
           System.out.println("I do something until you press Enter");
       }
   });
   Thread.ofVirtual().start(() -> {
        while (true) {
            doSomething();
            println("I'm blocked until you press Enter");
       }
   });
    readln("");
}
```